$83.6 \times 85.5 = $
Solution: ${8}$ ${3}$ ${6}$ ${8}$ ${5}$ ${5}$ ${\times\vphantom{0}}$ ${.}$ ${.}$ ${0.6}\times {0.5}= {0.30}$ ${0}$ ${3}\times {0.5}+C{0.3}= {1.8}$ ${8}$ ${80}\times {0.5}+C{1}= {41}$ ${1}$ ${4}$ ${0.6}\times {5}= {3.0}$ ${0}$ ${0}$ ${3}\times {5}+C{3}= {18}$ ${8}$ ${80}\times {5}+C{10}= {410}$ ${1}$ ${4}$ ${0.6}\times {80}= {48}$ ${8}$ ${0}$ ${0}$ ${3}\times {80}+C{40}= {280}$ ${8}$ ${80}\times {80}+C{200}= {6600}$ ${6}$ ${6}$ ${+\vphantom{0}}$ ${7}$ ${1}$ ${4}$ ${7}$ ${8}$ ${0}$ ${+\vphantom{0}}$ ${7}$ ${1}$ ${4}$ ${7}$ ${8}$ ${0}$ ${.}$ The top number has $1$ digit to the right of the decimal. The bottom number has $1$ digit to the right of the decimal. The product has $1+1=2$ digits to the right of the decimal. $83.6 \times 85.5 = 7147.80$